1. Field of the Invention
The present invention relates to a breather.
Further, the present invention relates to a breather which is installed to an apparatus such as an automatic transmission, for example, of a motor vehicle or the like, to regulate internal pressure of the apparatus by depressurization, etc. when the pressure in an internal portion of the apparatus is changed. Further, the present invention relates to a breather which is preferably attached to an upper portion of a sealed apparatus in which liquid is sealed in a sealed space.
2. Description of the Conventional Art
There has been conventionally known a breather as shown in Japanese Unexamined Patent Publication No. 2007-127139.
Since this kind of breather is structured such as to open and close a valve plate by a coil spring, not only the structure becomes complicated, but also the valve plate is opened more than necessary to cause a problem that fuel or working fluid within the apparatus tends to flow out, and muddy water or the like tends to make an intrusion from an external portion.
Accordingly, as a breather improved in these problematic points, there has been proposed a breather having a structure as shown in FIG. 3 (Japanese Unexamined Patent Publication No. 2001-355713).
The breather carries out exhaustion to reduce internal pressure in an inner portion of a case 600 through an exhaust passage 401 provided in the case 600, and recovers liquid such as oil or the like mixed in the exhaust passage 401 toward a liquid recovery passage 501 provided in the case 600.
The breather is constructed by a hexagon head bolt 200 fastened to a threaded hole 601 of the case 600, a cover 700 covering a periphery of the hexagon head bolt 200 to provide a surrounded space, and a compartment member 140 installed in the space formed by the cover 700.
The hexagon head bolt 200 is provided with a communication hole 201 formed in a shaft center from a leading end of a thread portion, and first and second passages 202 and 203 communicating orthogonally with the communication hole 201 and being open on an outer peripheral surface of a shaft portion.
The cover 700 is provided with a disc portion 701, and a cylinder portion 702 extending downward from a radially outer end of the disc portion 701.
The disc portion 701 is provided with an insertion hole 703 for inserting the hexagon head bolt 200 thereto.
Further, the cylinder portion 702 is provided with an exhaust hole 704 for exhaustion to an external portion.
The compartment member 140 is constructed by a metal ring 101, and a rubbery elastic body 102 integrally attached by baking to a periphery of the metal ring 101 and made of a material such as an acrylic rubber or the like.
The metal ring 101 is constructed by an annular portion 103, a first cylinder portion 104 bent upward from a radially inner end of the annular portion 103 so as to extend upward, and a second cylinder portion 105 bent downward from a radially outer end of the annular portion 103 so as to extend downward.
Further, the compartment member 140 is provided with a lip portion 106 extending in an upward and radially outer direction from a top face of the annular portion 103.
The compartment member 140 comparts the space within the cover 700 into an exhaust chamber 800 and a recovery chamber 900.
In the breather structured as mentioned above, when pressure within the case 600 rises beyond predetermined pressure, the lip portion 106 of the compartment member 140 is released from a contact state with the disc portion 701 of the cover 700 so as to become in a open state, the exhaustion to an external portion is carried out through the exhaust hole 704 from the exhaust chamber 800, and the internal pressure is reduced.
Further, in the case that liquid such as oil or the like exists much in the inner portion of the case 600, the liquid such as oil or the like is conducted into the communication hole 201 from the exhaust passage 401, and the liquid such as oil or the like within the communication hole 201 moves upward within the communication hole 201 in accordance with the rise of the internal pressure.
In this case, since the communication hole 201 is provided with the first passage 202, the liquid such as oil or the like flows into the first passage 202.
Accordingly, the liquid such as oil or the like is conducted to the recovery chamber 900 via the first passage 202, and is recovered into an inner portion of the case 600 from the recovery chamber 900 through the liquid recovery passage 501.
However, the liquid such as oil or the like which comes above the first passage 202 and flows out of the second passage 203 is hardly recovered, and there is a high risk of passing through the lip portion 106 so as to be discharged to an external portion.
Particularly, in the case that the internal pressure within the case 600 rapidly rises, this tendency is significant.